TURBINE GENERATOR PKG ERECTION PART-VIII, PLACEMENT OF LP TURBINE- ABC OF THERMAL POWER PLANT.

Part –VIII

Some measurements are taken during assembly of modular IP Turbine.

Journal diameter and corresponding Bearing-bore. Records the value.

Spigot and Recess dimensions of Couplings. Record the value

Out of flatness of coupling Faces (within 0.02 mm concave) & Coupling hole diameter. 

IP Casing Assembly clearances. Record the value and compare with shop result

Alignment of IP Outer Casing w.r.t. Pedestal.

Alignment of Lower Halves of IP Outer and Inner Casing (with Radial & Axial Keys)

Parting Plane gap in Inner Casing after tightening of alternate Bolts (0.02 to 0.03 mm).

Alignment of bearings w.r.t. Rotor. Record shim thickness.

Spring setting of IVCV. Ensure mechanical cleaning of Piping from IVCV to IP Inlet.

Heat tightening of IP Inlet connection & IP Outer Casing

Tightness of bolts at IP Inlet connection

ASSEMBLY OF LP MODULE

In turbine package LP Turbine takes maximum time because the turbine comes in

loose and need to be assembled at site. The job is voluminous and need constant

supervision and measurement.

This assembly can be divided in following sub assemblies

-Assembly of girder and end walls.

-Assembly of LP inner- inner casing and LP inner outer casing lower half.

-Assembly / welding of LP outer casing.

Before starting assembly of LP casing in position, following works are also to be completed :

- Positioning and welding of LP casing centring pin of front and rear side.

- Positioning of key block of LP casing axial keys.

 

- Positioning of all internal of condenser.

 

Two nos. centring pins are to be located below LP front and LP rear pedestal. Necessary pipe

along with two sq. end plates are already provided in the foundation to take the radial load

of the LP casing:

Plumb the centre line from LP front and LP rear pedestal bore on both side over the square

plate of the foundation.

Establish accurate position of the pin and put a punch mark at a required height and mark a

circle and a controlling circle over all the four sq. Plates.

Diameter of the circle must be equal to pin dia. A template equivalent to pin diameter has

to be made for this purpose with about 20 mm thick plate . The template diameter should

be precise.

Make precise hole to match template on all four embedded plate. Ensure that the template

is fitted with minimum clearance and hole centres are perfect as per marking.

Drill hole of about 10 mm diameter on one of square plate of LP front and on one plate of LP rear

for air venting to avoid cracks during welding.

Insert both the pins and carry out the welding as per laid down procedure. Before welding

set correct axial position of the pins.

Insert key block on both the pins and weld their locking ring also. Ensure proper clearances in key

 

block before welding of its locking ring.

Check the welding by DP test.

ASSEMBLY OF GIRDER AND END WALL

Match side matching flange of girder with the surface plate.

Match seating flange of girder where it rests over the LP base plate.

Match and ensure correct positioning of axial key ways of girder.

Colour match side flanges of end wall.

Match and ensure  key block of end wall are parallel.

Place left and right girder with carrier plate, spacer and special packer on LP base plate.

 

Provisionally align and level the girders. Set height of the girder equivalent to machine

centre line maintaining catenaries of the machine.

Assemble locking plate of the front and rear end wall to facilitate its assembly with the

girders.

Assemble front and rear end wall with the girders and ensure perfect parting plane level

during tightening.

Align, level LP outer casing and ensure contact of packers by colour matching/machining of

spacer height.

Install LP casing radial and axial keys.

Assemble inner outer casing axial key blocks on left and right side of girder and dowel them.

Lock with tack welding all the vertical joint bolts.

Put a seal weld run between girder and end wall joint all around except on top face.

Weld girder and end wall parting plane joint with argon welding. Before welding make a V

groove with the help of a chisel and allow the projection of material on surface. Do not

make the groove by grinding.

Do colour matching with a surface plate on all four corner where argon welding have been

carried out.

ASSEMBLY OF LP INNER INNER AND LP INNER OUTER CASING LOWER HALF

Clean the casing and check all the threaded holes.

Do colour matching on all four corners of the casing where it rest over the girder.

Colour match all eight carrier plates of inner casing on both side.

Assemble all carrier plates on girder and do the colour matching with individual carrier

plate.

Prepare Gusset plate of front and rear side with temporary radial keys for fitting in LP inner

casing.

Level and lift LP inner outer casing and assemble/weld both the gusset plates with the help

of some temporary support.

Lower the casing in position over the carrier plates fitted with spacer and special packer.

Provisionally align the casing radial and axial position.

Support the gusset plate with the help of screw jack (about 10-15 tons) on front and rear

side by taking support from condenser stiffeners. Screw jack is to be unscrewed after box-

up.

Adjust the height of the LP inner outer casing as per centre line of the machine and then

level it with the help of instrument.

Ensure that all the eight packers have good contact. Loading of each packer is to be ensured.

Lower the casing by about 2 mm on all the eight packers with the help of shims for

placement of LP rotor to avoid any fouling during placement of rotor.

Fit and weld all gusset plate stiffener pipes except pipe between LP inner outer casing and

condenser. Till neck welding is over do not make any weld connections between condenser

and stiffeners.

LP Turbine placement of a 660MW unit.

HP Turbine with ESV and HPCV , IP Turbine , LP Turbine Lowe casing , Generator ETC is shown

Continued to part -ix